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 > DC-DC battery charger - Is the Grail hunt over ?

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theoldwizard1

SE MI

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Posted: 03/20/18 09:02am Link  |  Quote  |  Print  |  Notify Moderator

While "wandering around" the internet, I found a relatively new product. It is a DC-DC battery charger, designed SPECIFICALLY for charging a "house" battery from your vehicle charging system while driving ! In theory THE GRAIL QUEST IS OVER !!
'
The CTEK D250SA takes current from your vehicle charging system as low as 11.5V and boost it up to the appropriate level for doing a multi-step charge on your house battery ! Additional features:
  • Isolation between vehicle battery and house battery when the ignition is OFF
  • Input from solar array (up to 23V and 300W) and does propper MPPT charging
  • Different charge profile for AGM house batteries
  • Back "trickle charge" vehicle battery if it is low and there is adequate solar power


The downside is, it is limited to 20A, but you are not likely going to be able to push more than 20A through a typical 7 pin trailer connector anyway. (They do make an option that will do 120A but now you are likely going to need ZERO gauge wire !)

EDIT - The older D250S does not have the capability to properly charge AGM batteries, but it does cost less.

* This post was last edited 03/20/18 01:50pm by theoldwizard1 *   View edit history

SoundGuy

S Ontario

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Posted: 03/20/18 03:36pm Link  |  Quote  |  Print  |  Notify Moderator

theoldwizard1 wrote:

While "wandering around" the internet, I found a relatively new product. It is a DC-DC battery charger, designed SPECIFICALLY for charging a "house" battery from your vehicle charging system while driving ! In theory THE GRAIL QUEST IS OVER !!
'
The CTEK D250SA takes current from your vehicle charging system as low as 11.5V and boost it up to the appropriate level for doing a multi-step charge on your house battery ! Additional features:
  • Isolation between vehicle battery and house battery when the ignition is OFF
  • Input from solar array (up to 23V and 300W) and does propper MPPT charging
  • Different charge profile for AGM house batteries
  • Back "trickle charge" vehicle battery if it is low and there is adequate solar power


INTERESTING! [emoticon]

I recently ordered a Deka G31 AGM to replace my aged tongue mounted flooded G27. This new G31 is going in the trailer's front pass through cargo compartment so I can use short 18" 1 or 2 gauge cables to connect to my 1000 watt PSW inverter. I already own a CTEK Multi US 7002 that properly bulk charges at 14.4 volts and will use it instead of the trailer's WFCO which never charges beyond ~ 13.7 volts. Yes, it's only a 7 amp charger and no it doesn't offer temp compensated charging but since we normally camp on electric sites I don't significantly draw the battery down more than a few times each season and therefore don't often have the need for significant recharging.

As such, I only use the inverter a few times each season when shore power fails or isn't available and because of this I've been reluctant to invest in two batteries when I otherwise have no need for that much reserve. Those few times each season I do use the inverter I've found that load supporting the one battery with the truck (running) by connecting to it with heavy gauge booster cables is sufficient to prevent excessive voltage drop when the inverter is under brief but heavy load measuring up to ~ 60 amps from the toaster or coffee maker. Now here's the interesting part - my 2012 Silverado has an empty spot next to the under hood fuse box that's designed to hold a second battery up to G24 size, but no larger ... for what reason this space is there I don't know, it just is. [emoticon] I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery. The one G24 in the trailer would certainly serve our normal needs yet still get us through one night of camping without shore power. On those few occasions when I do use the inverter I could load support the trailer battery with the second auxiliary battery in the truck, knowing it would always be maintained at a 100% SOC. It therefore seems to me the only drawback is that on occasion I might have to swap out the trailer battery with the truck aux battery for recharging with the DC charger ... OTOH that certainly would be convenient to be able to recharge while just driving around in the truck! Hmmmm, maybe this new CTEK DC charger is indeed the Holy Grail for those of us with limited battery requirements, who don't want to drag along a genset, or aren't really all that interested in solar that only works when the sun is out anyway. Hmmmmm.

Thoughts anyone? [emoticon]

theoldwizard1

SE MI

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Posted: 03/20/18 04:01pm Link  |  Quote  |  Print  |  Notify Moderator

SoundGuy wrote:

I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery.

Do NOT replace the flooded lead acid battery in your truck with an AGM battery ! Your trucks charging system will NOT properly charge it, leading to a short life.

time2roll

Southern California

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Posted: 03/20/18 04:16pm Link  |  Quote  |  Print  |  Notify Moderator

$300 is a bit much unless there is a serious issue to resolve or have extraordinary needs.


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

theoldwizard1

SE MI

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Posted: 03/20/18 05:26pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

$300 is a bit much unless there is a serious issue to resolve or have extraordinary needs.

It has been covered MANY TIMES before, that simply connecting your RV battery in parallel with the TV battery, even using LARGE cable will not fully charge your RV battery !

If you want to charge while you are driving, you need something like this. Period. End of discussion.

SoundGuy

S Ontario

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Posted: 03/20/18 05:39pm Link  |  Quote  |  Print  |  Notify Moderator

SoundGuy wrote:

I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery.


theoldwizard1 wrote:

Do NOT replace the flooded lead acid battery in your truck with an AGM battery ! Your trucks charging system will NOT properly charge it, leading to a short life.


Where did I say anything about replacing the truck starting battery? [emoticon] If you believe I did you should re-read my post so you understand I'm talking about putting one G24 AGM in the trailer, a second in the currently empty spot in the truck designed for an aux battery, and investing in this CTEK DC charger to maintain that aux battery. How has this got anything at all to do with the truck's starting battery? [emoticon]

theoldwizard1

SE MI

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Posted: 03/20/18 06:27pm Link  |  Quote  |  Print  |  Notify Moderator

SoundGuy wrote:


Where did I say anything about replacing the truck starting battery? [emoticon] If you believe I did you should re-read my post ...

My apologies.

richconn

Amarillo, TX

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Posted: 03/20/18 07:20pm Link  |  Quote  |  Print  |  Notify Moderator

Check out lslproducts.com Using trickle start on my Itasca. Works great.

mike-s

Michigan

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Posted: 03/20/18 07:37pm Link  |  Quote  |  Print  |  Notify Moderator

theoldwizard1 wrote:

It has been covered MANY TIMES before, that simply connecting your RV battery in parallel with the TV battery, even using LARGE cable will not fully charge your RV battery !
No, but it can get it to 90%, and that's only an issue if your bank is underrated for the need, or you don't have any opportunity to fully top off every week or two via other methods.

SoundGuy

S Ontario

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Posted: 03/21/18 04:11am Link  |  Quote  |  Print  |  Notify Moderator

SoundGuy wrote:

I'm just thinking out loud here but maybe instead of the single G31 for the trailer I should buy two G24 AGMs, put one in the trailer as planned & the second in the truck, and invest in this new CTEK 12 volt charger to maintain this truck auxiliary battery.


theoldwizard1 wrote:

Do NOT replace the flooded lead acid battery in your truck with an AGM battery ! Your trucks charging system will NOT properly charge it, leading to a short life.


SoundGuy wrote:

Where did I say anything about replacing the truck starting battery? [emoticon]


theoldwizard1 wrote:

My apologies.


No worries, I re-read my post yet again to make sure I was clear in how I thought I could take advantage of this new CTEK DC charger, and I think I was. [emoticon] Over the winter I've been considering upgrading from my current CTEK Multi US 7002 7 amp charger to a CTEK 25000 Multi US 25 amp charger featuring temp compensated charging that would be more suitable for maintaining a costly AGM battery. However, now that you've brought this new CTEK DC charger to our attention I'm thinking this may be a better option, even if it means removing the battery from the trailer to the truck those few times each season I may need to recharge it before we get home. It's a conundrum - I really don't need the reserve capacity of dual G24a on a regular basis, yet that space GM provided in my Silverado for an auxiliary battery isn't big enough for a G31 ... arrghhh. [emoticon] I'm going to have to take another look to see if there isn't some way I could squeeze a G31 in there ... if so, I'd buy this new DC charger instead of the 120 vac CTEK 25000 so I could recharge the G31 while driving. Anyway, thanks for the heads up on this new charger. [emoticon]

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